GCSE Maths Foundation · AQA · Order of operations & negatives
Squaring a negative: (−8)² = 64, and −4² is not (−4)²
Squaring a negative trips students two ways. First, they keep the minus, writing when squaring multiplies the number by itself and a negative times a negative is positive, so . Second, they read and as the same, when the bracket decides: but .
The thirty-second fix: squaring a negative always gives a positive, because the two minus signs cancel — and the bracket decides what gets squared, so −4² means −(4²) = −16, while (−4)² squares the whole −4 to give 16. So , and the killer pair is versus .
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How to spot it in your own work
- You kept the minus on a square, writing instead of 64 — a negative times a negative is positive.
- You read and as the same, when they are and .
- You squared the whole of as if it were bracketed, getting 16 instead of — without a bracket the square reaches only the 4.
- You substituted a negative into and left the answer negative, e.g. taking as rather than .
An exam question that triggers it
Here is a canonical AQA Foundation trigger (non-calculator paper, work out the value):
Work out
The misconception is to carry the minus through and write , as if squaring kept the sign. But squaring means , and a negative times a negative is positive.
The two minus signs cancel: . Squaring any negative gives a positive result.
Why students fall for this
A minus sign feels like it should travel with the number, so squaring it looks like it ought to keep it — hence . But squaring is multiplying the number by itself, and . Two negatives multiplied give a positive, so the minus signs cancel and the answer is . Every squared negative comes out positive for the same reason.
The bracket version is sharper. and look almost identical but are not equal, because powers are worked out before the minus is applied unless a bracket forces the minus inside first. Without a bracket, means : square the 4, then apply the minus. With a bracket, makes a single value that is squared, so .
AQA Foundation papers exploit both directly: evaluating a bracketed square like , and substituting a negative into an expression with where the bracket — or its absence — fixes the sign.
Worked example — the killer pair. Work out and .
No bracket means the square reaches only the 4; a bracket means the whole is squared:
The trap is to treat them as the same. They differ only by the bracket, and the bracket is the whole point: against .
The fix: Squaring a negative gives a positive; the bracket decides what gets squared
Squaring multiplies the number by itself. , and a negative times a negative is positive, so the answer is — the minus signs cancel.
A squared negative is always positive. Whatever the digits, comes out positive, because you are multiplying two negatives.
Look for the bracket. With a bracket, the whole negative is squared: . Without one, the square attaches to the digit only and the minus stays outside: .
When substituting, bracket the negative. Putting into means , not — write the bracket so the square reaches the whole value.
Worked example
Work out , then compare with . These are the two traps: keeping the minus on a square, and missing the bracket.
- Write the square as a product. .
- Cancel the signs. A negative times a negative is positive, so The trap answer keeps a single minus that should have cancelled.
- Square without the bracket. has no bracket, so the square reaches only the 4: .
- Square with the bracket. Same digits, opposite signs: but . The bracket is the whole difference.
So a squared negative is positive whenever the negative is bracketed, and the opening trigger is — not the you get by carrying the minus through the square.
Find out if this is costing you marks
The 10-minute diagnostic checks for this pattern (and four others) using AQA-style GCSE Higher items. Free, no signup, anonymous.
Common questions
- What is ?
It is 64, not . Squaring means multiplying the number by itself, and . A negative times a negative is positive, so the two minus signs cancel and the answer is . Leaving it as keeps a single minus sign, but squaring a negative always gives a positive result.
- Is the same as ?
No. , but . The bracket decides what gets squared. In the whole of is squared, so . In there is no bracket, so by order of operations the square attaches to the 4 only: it means . The minus sits outside the squaring.
- Why does the bracket change the answer when squaring a negative?
Because powers are worked out before the minus sign is applied, unless a bracket forces the minus inside first. Without a bracket, is read as : square the 4 to get 16, then apply the minus for . With a bracket, makes a single value that is squared, so . Same digits, opposite signs — the bracket is the whole difference.
Related misconceptions
- Ordering and signs of negative numbersThe underlying sign rules: a negative times a positive is negative and further left is smaller, so −3 × 3 = −9 and −7 < −5.
- Order of operations: × and ÷ before + and −Why the bracket matters at all: powers and brackets come before the rest, so −4² means −(4²) while (−4)² squares the whole value.